Swainson's Hawk

A classic species of the open country of the Great Plains and the West, Swainson’s Hawks soar on narrow wings or perch on fence posts and irrigation spouts. These elegant gray, white, and brown hawks hunt rodents in flight, wings held in a shallow V, or even run after insects on the ground. In fall, they take off for Argentine wintering grounds—one of the longest migrations of any American raptor—forming flocks of hundreds or thousands as they travel.

Typical Voice

Size & Shape

Swainson’s Hawks are buteos, meaning they are large hawks with fairly broad wings and short tails. However, Swainson’s Hawks are less hefty than many other buteos. They are slimmer and longer-winged, with their wings typically held in a shallow V when soaring.

Color Pattern

Though they can be quite variable, most Swainson’s Hawks are light-bellied birds with a dark or reddish-brown chest and brown or gray upperparts. They have distinctive underwings with white wing linings that contrast strongly with blackish flight feathers. Most males have gray heads; females tend to have brown heads. Dark individuals also occur; these vary from reddish to nearly all black, with reduced contrast on the underwings.

Behavior

Swainson’s Hawks are social raptors, nearly always being found in groups outside the breeding season. You may see them soaring in a kettle of migrating birds; strung out on the ground, fence posts, and utility poles when foraging on grasshoppers; or chasing swarms of dragonflies on winter quarters in Argentina.

Habitat

These hawks spend summers in the wide-open spaces of the American West. They are the typical nesting buteo of grasslands, but also use sage flats and even swaths of agriculture intermixed with native habitat. Nests are placed in trees, often in the only tree visible for miles.

Similar Species

Light-plumaged adult Swainson’s Hawks are distinctive because of the contrast on their chest and belly and also on their underwings. Darker birds and immatures can be tricky. Light adult Red-tailed Hawks have shorter, wider wings without the strong light-to-dark wing contrast and dark trailing edge of Swainson’s Hawk. Light Ferruginous Hawks typically are entirely light from breast to belly, and the wings are white from below. Rough-legged Hawks (even light adult males) have an obvious black-and-white tail pattern and their legs are feathered to the toes. Dark Red-tailed, Ferruginous, and Rough-legged hawks typically have dark wing linings and paler flight feathers, where dark-morph Swainson’s show either the opposite pattern or, rarely, entirely dark underwings. Immature Red-tailed, Ferruginous, and Rough-legged hawks also sport a translucent panel in the outer wing, unlike Swainson’s Hawk. The White-tailed Hawk of coastal Texas has an obviously white tail with a distinct black band. Immature White-taileds are mostly dark, but usually have a white patch on the chest, unlike Swainson’s.

Regional Differences

Nearly all Swainson’s Hawks breeding in the eastern half of the range (east of the Rocky Mountains) are light in appearance. Darker-plumaged birds are more common in the West, although still in the minority, accounting for upwards of 10 percent of individuals.

Find This Bird

Your best bet for finding Swainson’s Hawks is during summer in open country west of the Mississippi River. They are perch conspicuously on utility poles, fence posts, and isolated trees in areas that otherwise lack such elevated perches. In perch-deprived areas, look for them standing on the ground in grassland or tilled agricultural fields. No other buteo species can be found in large numbers in such situations. During migration, they don’t move along ridgelines or lakeshores nearly as much as do other raptors. Instead, look for large flocks of soaring raptors over open country within their range, especially in April and September. If these are not Turkey Vultures, they are almost certainly Swainson's Hawks. At a few select migration spots including Hazel Bazemore Park (Corpus Christi, Texas) and a few sites in Middle America (Veracruz, Mexico; Kèköldie, Costa Rica; and Panama City, Panama) you can reliably see very large numbers of them passing south in fall. You can also see fairly large numbers in spring at the Santa Ana National Wildlife Refuge hawkwatch in south Texas.